U.S. patent application number 13/065563 was filed with the patent office on 2011-07-14 for flexible tubing with dual-level imbedded helical conductors and method of making.
This patent application is currently assigned to Steward Plastics, Inc.. Invention is credited to Eric Carlson.
Application Number | 20110168287 13/065563 |
Document ID | / |
Family ID | 44257590 |
Filed Date | 2011-07-14 |
United States Patent
Application |
20110168287 |
Kind Code |
A1 |
Carlson; Eric |
July 14, 2011 |
Flexible tubing with dual-level imbedded helical conductors and
method of making
Abstract
A smooth-bore plastic tubing with an outer helical support bead
is resistant to collapse and incorporates plural conductors
disposed outside of the tubing bore and insulated both from ambient
and from one another. The conductors may have a desired relatively
high thermal conductivity to tidal air flow within the tubing,
while also having a comparatively high thermal resistance to
ambient. The conductors may be electrical conductors, or may
include fiber optic conductors as well in the same tubing
structure.
Inventors: |
Carlson; Eric; (Laguna
Hills, CA) |
Assignee: |
Steward Plastics, Inc.
|
Family ID: |
44257590 |
Appl. No.: |
13/065563 |
Filed: |
March 24, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11903898 |
Sep 25, 2007 |
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13065563 |
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Current U.S.
Class: |
138/108 ;
138/129; 493/297 |
Current CPC
Class: |
F16L 11/16 20130101;
F16L 11/081 20130101; F16L 57/02 20130101; B29C 53/78 20130101;
F16L 11/127 20130101 |
Class at
Publication: |
138/108 ;
138/129; 493/297 |
International
Class: |
F16L 55/00 20060101
F16L055/00; F16L 11/00 20060101 F16L011/00; B31C 99/00 20090101
B31C099/00 |
Claims
1. A thin-walled, flexible and collapse-resistant thermo-plastic
tubing having a substantially smooth bore and a helical outer
support bead structure, the tubing including plural conductors
helically disposed within said support bead structure, said tubing
comprising: a flexible tubing wall formed of an elongate primary
thermo-plastic ribbon including a comparatively thinner wall
portion and a comparatively thicker bead-foundation plateau
portion, said plateau portion defining plural elongate
fine-dimension grooves, said primary ribbon while molten being
helically wrapped repeatedly on itself to overlap successive wraps
of said primary ribbon a certain amount forming a helical lap joint
where successive wraps of said primary ribbon heat-bond integrally
to one another so that an elongate tubing body is formed; plural
elongate conductors each disposed individually in a respective one
of said fine-dimension grooves of said plateau portion and
helically around and along said elongate tubular body; a secondary
elongate thermoplastic ribbon while molten being helically wrapped
repeatedly on said plateau portion of said primary ribbon and
heat-bonding integrally thereto to capture said plural elongate
conductors; at least one additional conductor helically wrapped
onto said secondary ribbon to dispose at a radially outer location
relative to said plural conductors; and an elongate thermoplastic
support bead portion disposed helically around and along said
elongate tubular body atop of said plateau portion and said
secondary ribbon while molten, said support bead portion integrally
heat-bonding to said secondary ribbon so that said plateau portion,
said secondary ribbon, and said support bead portion cooperatively
form said bead structure, and said tubing comprises a unitary
thin-walled tubing structure with helical outer support bead and
embedded conductors extending helically about and along said
tubing.
2. The tubing of claim 1 wherein said plural conductors include at
least one resistance conductor for providing resistance heating to
said tubing.
3. The tubing of claim 1 wherein said plural conductors include at
least one instrumentation conductor for conducting an
instrumentation signal along a length of said tubing.
4. The tubing of claim 1 wherein said plural conductors include at
least a twisted pair set of instrumentation conductors for
conducting an instrumentation signal along a length of said
tubing.
5. The tubing of claim 1 wherein said secondary ribbon defines at
least one elongate groove extending helically about and along said
tubing, and at least one conductor disposed within said secondary
ribbon at a radially outwardly spaced location relative to said
conductors disposed within said plateau portion.
6. The tubing of claim 1 wherein said secondary ribbon is free of
elongate grooves when placed upon said plateau portion, and said
secondary ribbon responding to a difference in compliance of said
tubing structure over said conductors to form elongate recesses
extending helically about and along said tubing, and a conductor
disposed in at least one of said elongate recesses to extend
helically about and along said tubing.
7. A method for making a helically wound, seamless plastic tubing
comprising the steps of: forming an elongate ribbon of molten
thermoplastic having a thin portion and a thickened plateau portion
including at least one elongate groove, helically wrapping said
elongate ribbon so that said plateau portion overlaps a part of
said thin portion to form a helical lap joint and simultaneously
heat-bonding said ribbon to itself to form an elongate tubular body
with said plateau portion extending radially outwardly on and
helically along said tubular body; laying an elongate conductor
helically around and along said tubular body within said at least
one elongate groove of said plateau portion; forming an elongate
fine-dimension secondary ribbon; placing said fine-dimension
secondary ribbon helically about and along said tubular body at
said plateau portion to heat bond thereto; placing another
conductor atop of said fine-dimension secondary ribbon helically
about and along said tubular body; and forming an elongate bead of
thermoplastic material; and helically wrapping said bead about and
along said tubular body atop said conductors and plateau portion,
while simultaneously heat-bonding said bead integrally with said
tubular body to form a unitary tubing including said ribbon and
said bead with said conductors embedded therein.
8. The method of claim 7 wherein the step of forming said elongate
ribbon further includes the step of forming plural elongate grooves
extending along said plateau portion, and providing for said
elongate grooves to extend helically about and along said tubular
body.
9. The method of claim 8 further including the steps of utilizing
said plural grooves to define plural ribs on said plateau
portion.
10. The method of claim 9 further including the step of providing
for said plural ribs to include an outer pair of ribs bracketing
the remainder of said plural ribs and said plural elongate grooves
therebetween, and providing for said grooves and ribs to
cooperatively guide plural conductors into repose within said
plural grooves of said plateau portion.
11. The method of claim 9 further including the steps of forming
said elongate fine-dimension secondary ribbon with at least one
elongate groove bracketed by a pair of shoulders.
12. The method of claim 11 further including the step of providing
for a conductor to wrap about and along said tubular body within
said at least one elongate groove of said fine-dimension secondary
ribbon.
13. The method of claim 11 further including the step of disposing
a twisted pair conductor said plural ribs to include an outer pair
of ribs bracketing the remainder of said plural ribs and said
plural elongate grooves therebetween, and providing for said
grooves and ribs to cooperatively guide plural conductors into
repose within said plural grooves of said plateau portion.
14. A smooth-bore flexible tubing with helical outer support bead,
said tubing comprising: an elongate thermoplastic ribbon helically
wrapped and partially overlapped onto itself and mutually heat
bonded to itself to form a flexible tubing, said thermoplastic
ribbon including an elongate fine-dimension portion and a
comparatively thickened elongate plateau portion extending radially
outwardly and helically about and along said flexible tubing;
plural conductors disposed helically about and along said flexible
tubing at said plateau portion; a secondary fine-dimension
thermoplastic ribbon wrapped about and along said tubing at said
plateau atop of said plural conductors; at least one additional
conductor wrapped about and along said tubing atop of said
secondary fine-dimension thermoplastic ribbon to dispose at a
radially outer location relative to said plural conductors; and an
elongate thermoplastic support bead disposed helically around and
along said tubing atop of said plateau portion and said secondary
fine-dimension thermoplastic ribbon as well as atop of said
conductors, said support bead integrally heat-bonding to said
tubing to form a unitary thin-walled tubing structure with helical
outer support bead and embedded conductors, whereby, said embedded
conductors are spaced from one another.
15. The tubing of claim 14 wherein said plural conductors include
at least one resistance conductor for providing resistance heating
to said tubing.
16. The tubing of claim 14 wherein said plural conductors include a
pair of electrically connected resistance conductors for providing
resistance heating to said tubing.
17. The tubing of claim 14 wherein said at least one conductor
disposed at said secondary fine-dimension ribbon includes a twisted
pair conductor set.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a Continuation-In-Part of co-pending and
allowed U.S. patent application Ser. No. 11/903,898, now U.S. Pat.
No. ______, granted ______, the disclosure of which is incorporated
herein by reference to the extent necessary for a complete enabling
disclosure of the present invention.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to
collapse-resistant, flexible thermoplastic tubing, to such plastic
tubing which includes plural helical conductors extending along the
length of the tubing at a duality of radial levels, and to a method
for making such flexible plastic tubing.
[0004] 2. Description of Conventional Technology
[0005] Tubing having a relatively thin wall and an integral helical
supporting bead is known in the art. Such support-bead tubing
construction provides substantial crush resistance while leaving
the tube wall flexible enough to permit short-radius bends without
collapsing or kinking the tube. The versatility of this kind of
tubing is evidenced by its wide applicability in construction,
ventilation, manufacturing processes, auto washes, hospitals,
medical devices, and other fields. In medical applications the
necessity to maintain a clean environment dictates that the tubing
be free of crevices both inside and outside because soil or
bacterial contamination could reside in such crevices were they
present. A smooth inner bore for the tubing is also important
because flow resistance must be kept to a minimum when a tidal air
flow is conducted through the tubing, as is the case with
inhalation therapy, CPAP (Continuous Positive Airway Pressure) and
other breathing-assistance machines.
[0006] U.S. Pat. No. 3,910,808 to Steward, assigned to the same
assignee as this application, discloses apparatus for forming such
thin-walled, flexible, crush resistant support-bead tubing. Steward
discloses means for extruding a plastic strip having a longitudinal
rib, and winding means for helically winding the strip about an
axis to produce a corrugated flexible tubing having a smooth
bore.
[0007] Further, U.S. Pat. No. 5,454,061, also to Steward, discloses
apparatus for forming such thin-walled, flexible, crush resistant
support-bead tubing also including a helically disposed conductor.
Steward '061 discloses a tubing in which the conductor is disposed
adjacent to overlapping side edges of an extruded plastic strip or
ribbon, which is wrapped helically on itself while molten to form
the tubing wall. The overlapped edges of the ribbon as well as the
conductor are then helically covered with an extruded molten bead,
which also bonds with and becomes an integral part of the
tubing.
[0008] With the Steward '061 tubing, and with other conventional
tubing, when plural conductors are disposed in the tubing wall,
they are immediately adjacent to one another. In some applications
when the conductors are used for warming, heating, or maintaining
the temperature of a tidal air flow in the tubing by means of
resistance heating, for example, the heating from these conductors
is concentrated at their location. It may be desirable for the
conductors to not be immediately adjacent to one another so that
heating is somewhat more dispersed. Further, when plural conductors
are disposed in such a tubing wall, and one or more of the
conductors is utilized for conducting instrumentation or telemetry
signals, then it is also desirable for the conductors to be spaced
apart a controlled and determined distance for purposes of
preserving signal clarity and fidelity, for insuring electrical
insulation between the conductors, and for preventing or reducing
mutual inductive coupling among the conductors, including the
heating conductors and the signal conductors.
[0009] No prior product, method of manufacture, or apparatus is
known which provides a thin-walled, smooth-bore tube having plural
spaced apart conductors helically imbedded at two radial levels in
the outer structure of the tube and which conductors are available
for heating of tidal air flow in the tube, as well as for
instrumentation or telemetry signals to be conducted along the
length of the tube, for example, all with a helically ribbed but
substantially crevice-free outer surface.
[0010] Those ordinarily skilled in the pertinent arts and familiar
with U.S. Pat. No. 3,910,808 to Steward will understand that tubing
of the type described in this application is generally manufactured
using an apparatus including a winding or wrapping head having
plural (usually 4) cantilevered and rotationally driven winding
rolls. These winding rolls are canted both axially and radially,
and are spaced about a longitudinal axis for winding and
rotationally advancing a helically wound and ribbed flexible
tubing. The winding rolls rotate in unison while a molten plastic
ribbon is helically wrapped on itself and integrally heat bonds to
form a spinning and axially advancing tubing wall. The tubing is
cooled internally and externally by air or water, or a combination,
delivered and directed onto the forming tubing so as to allow the
molten plastic ribbon and other parts to fuse, and to accomplish
solidification and cooling of the plastic. While the tubing is
being formed, conductors are placed on the tubing wall, and an
outer molten bead is wrapped helically along the tubing wall atop
of the conductors. The bead integrally heat bonds to become a part
of the tubing wall. The tubing is cooled finally in an immersion
water bath, and is then cut into determined lengths.
SUMMARY OF THE INVENTION
[0011] In view of the deficiencies of the related art as discussed
above, it is a primary object of the present invention to provide a
flexible, lightweight, crush-resistant tubing having plural spaced
apart conductors, and a conductor-supporting bead, helically wound
about and integral with the wall of the tubing.
[0012] It is another object of this invention to provide such a
tubing in which the wall of the tubing provides an elevated helical
plateau, in which plural helical grooves or crevices are defined,
and into which the plural conductors are disposed and spaced
uniformly and helically about and along the length of the tubing,
to there be integrally covered by a support bead.
[0013] Still another object for this invention is to provide a
tubing as described immediately above, and in which the support
bead itself includes a radially inner portion which outwardly
defines at least one helical groove or crevice into which at least
one additional conductor is received. An upper or cap portion of
the support bead retains and protects the additional conductor.
[0014] These and other objects are achieved by the present
invention which provides: a thin-walled, flexible and
collapse-resistant thermo-plastic tubing having a substantially
smooth bore and a helical outer support bead structure, the tubing
including plural conductors helically disposed within the support
bead structure, the tubing comprising: a flexible tubing wall
formed of an elongate primary thermoplastic ribbon including a
comparatively thinner wall portion and a comparatively thicker
bead-foundation plateau portion, the plateau portion defining
plural elongate fine-dimension grooves, the primary ribbon while
molten being helically wrapped repeatedly on itself to overlap
successive wraps of the primary ribbon a certain amount forming a
helical lap joint whereat successive wraps of the primary ribbon
heat-bond integrally to one another so that an elongate tubing body
is formed; plural elongate conductors each disposed individually in
a respective one of the fine-dimension grooves of the plateau
portion and helically around and along the elongate tubular body; a
secondary elongate thermoplastic ribbon while molten being
helically wrapped repeatedly on the plateau portion of the primary
ribbon and heat-bonding integrally thereto to capture the plural
elongate conductors; at least one additional conductor helically
wrapped onto the secondary ribbon to dispose at a radially outer
location relative to the plural conductors; and an elongate
thermoplastic support bead portion disposed helically around and
along the elongate tubular body atop of the plateau portion and the
secondary ribbon while molten, the support bead portion integrally
heat-bonding to the secondary ribbon so that the plateau portion,
the secondary ribbon, and the support bead portion cooperatively
form the bead structure, and the tubing comprises a unitary
thin-walled tubing structure with helical outer support bead and
embedded conductors extending helically about and along the
tubing.
[0015] For resistance heating purposes, the wire conductor is
preferably formed of copper, although resistive metal such as
nickel-chromium may also be utilized. For telemetry purposes, the
conductor(s) may be any suitable conductive material, including
metals and conductive polymers, for example. A conductor which
conducts light may also be employed (i.e., a fiber-optic
conductor). Further, one or more of the conductors may comprise a
twisted-pair of electrical conductors, which provides unique
properties in terms of inductive and capacitive coupling among the
conductors.
[0016] Further applications of the present invention will be
apparent to those skilled in the art from a consideration of a
fully detailed exemplary embodiment thereof. To aid in the
explanation of the exemplary embodiment, reference will be made to
the figures of the appended sheets of drawings, which figures will
first be described briefly.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
[0017] The advantages and features of the present invention will be
better understood by the following description when considered in
conjunction with the accompanying drawings in which:
[0018] FIG. 1 provides an exterior view of a tubing according to
this invention;
[0019] FIG. 2 is a fragmentary cross sectional view of the tubing
seen in FIG. 1;
[0020] FIG. 3 provides a fragmentary cross sectional view of an
elongate section of the wall of the tubing seen in FIGS. 1 and 2
during manufacture;
[0021] FIG. 4 provides a fragmentary cross sectional view of an
elongate section of the wall of the tubing seen in FIGS. 1-3, at a
next-subsequent step of manufacture;
[0022] FIG. 5 provides a fragmentary cross sectional view of an
elongate section of the wall of the tubing seen in FIGS. 1-4, at a
next-subsequent step of manufacture;
[0023] FIG. 6 is a fragmentary cross sectional view of an elongate
section of the wall of the tubing seen in FIGS. 1-5, with
manufacture of the tubing completed;
[0024] FIGS. 7 and 8 provide a fragmentary cross sectional views of
an elongate section of an alternative embodiment of tubing, and are
similar to that of FIGS. 2 and 6, respectively, with the exception
that this alternative embodiment of tubing is realized by a
manufacturing process which is presently believed by the applicant
to offer advantages in simplicity and cost reduction; and
[0025] FIG. 9 provides a fragmentary cross sectional view of a
section of yet another alternative embodiment of tubing, and is
similar to FIGS. 2 and 7, with the exception that the steps of
manufacture of this alternative embodiment of tubing are shown in a
condensed version of the drawing Figure, and this alternative
tubing embodiment includes a twisted pair of electrical conductors
disposed at a radially outer level within a bead structure of the
tubing.
DETAILED DESCRIPTION OF EXEMPLARY PREFERRED EMBODIMENTS OF THE
INVENTION
[0026] Considering now FIGS. 1-6 in conjunction with one another,
and viewing first FIG. 1, it is seen that the tubing 10 according
to this invention has an exterior appearance essentially the same
as conventional tubing of this type. That is, the tubing has a
comparatively thin and flexible wall 12, and a helical bead
protruding somewhat above this wall and extending helically about
and along the length of the tubing. As will be seen, the tubing 10
also includes embedded conductors (not seen in FIG. 1) extending
helically in the bead 14 and along the length of tubing 10 from end
to end.
[0027] Viewing now FIG. 2, which illustrates both structures as
well as steps in the process of making the present inventive
tubing, it is seen that the wall 12 is formed by successive helical
wraps of an elongate thin thermoplastic primary ribbon 12'. This
thermoplastic primary ribbon 12' is initially in molten condition,
having just been discharged from the die of a plastic extrusion
machine (not seen in the drawing Figures). At the right-hand side
of FIG. 2, the most recently extruded portion of primary ribbon 12'
is about to touch down (note the slight gap "G") on a previously
extruded portion of primary ribbon 12' which is wrapped about
spinning winding rolls (also not seen in the drawing Figures).
Thus, the tubing structure forming in FIG. 2 is spinning about its
centerline, indicated at "CL."
[0028] The primary ribbon 12' includes a rather thin and flexible
portion 12a extending axially between adjacent beads 14 along the
length of the tubing 10, as seen in FIG. 1. This thin portion 12a
forms the wall 12 seen in FIG. 1. Primary ribbon 12' also includes
a somewhat thickened plateau portion 12b which is disposed beneath
the bead 14 seen in FIG. 1. That is, the plateau portion 12b is an
integral portion of the primary ribbon 12', and protrudes radially
outwardly relative to the thinner portion 12a to form a base or
foundation upon which the bead 14 is built up and secures.
[0029] As is seen best at the right hand end of FIG. 2, just before
the moment a successive wrap of the primary ribbon 12' touches a
preceding wrap (again, note the slight gap "G"), the wraps of
primary ribbon 12' are distinct from one another in axial cross
section (but are integral with one another helically along the
length of the ribbon 12'--that is, around the winding rolls), and
the successive wraps of primary ribbon 12' as they touch and
interbond form a wrap or overlap joint (note the overlap dimension
X, indicated on FIG. 2), as is generally indicated with arrowed
numeral 16.
[0030] In other words, as the wraps of primary ribbon 12' touch
they heat bond together, and as is seen at the next lap joint 16 to
the left in FIG. 2, the successive wraps of ribbon 12' have touched
at joint 16 and heat bonded to one another (i.e., the ribbon is
molten thermoplastic at this time), and the wraps of primary ribbon
12' are now integral with one another both helically and axially
along the length of the tubing 10. It is for this reason that the
cross hatching of FIG. 2 shows the tubing structure 10 becoming an
integral whole. The joint lines at what was once individual parts
or successive wraps of the primary ribbon 12' may be indicated in
the various drawing Figures with dashed lines as on FIG. 2 simply
as a reminder to the reader, but the structure of the plastic
tubing 10 is becoming a unity in FIG. 2. Again, it will be recalled
that the tubing 10 during manufacture is both spinning about its
axis (i.e., about centerline "CL"), and as it is formed is moving
leftwardly relative to the viewer of FIG. 2, as is indicated by the
left-facing arrow on FIG. 2. Also, the inner surface of the wraps
of primary ribbon 12' (i.e., disposed toward the centerline
indicated on FIG. 2) is being actively cooled by a water spray,
indicated on FIG. 2 by the arrow "W". Moreover, the change in
status of the successive wraps of ribbon 12' denoting the formation
of a integral tubular body is indicated on FIG. 2 by the successive
changes from distinct cross hatches, to an integral or uniform
cross hatch both for the successive wraps of ribbon 12' and other
parts of the tubing 10.
[0031] At the plateau portion 12b the primary ribbon 12' (and
tubing 10) includes plural spaced apart grooves 18 each bounded by
a respective rib part 20 of the plateau portion 12b. Disposed
within these grooves 18 and separated from one another by the ribs
20 are individual conductors 22 (viewing FIGS. 2 and 3). As will be
seen below, the conductors 22 need not be individually disposed in
the tubing 10, but may be disposed as a twisted pair, for example,
advantages of which are explained more fully below. But, the
embodiment of FIGS. 1-6 utilizes individual conductors disposed in
the tubing 10 beneath bead 14, and running in parallel helically
about and from end to end of a length of the tubing 10. It will be
understood that the conductors 22 are wrapped into the grooves 18
as the progressively forming tubing 10 spins on the wrapping rolls
described earlier.
[0032] Next, a thin, elongate, fine-dimension, secondary ribbon 24
is extruded (i.e., as molten plastic) and is placed on top of the
plateau 12b. This secondary ribbon is first seen at the third lap
joint 16 to the left in FIG. 2, in a position just before alighting
on the plateau 12b (again, note the slight gap "G"). A moment later
in the manufacturing process as illustrated in FIG. 2, the
secondary ribbon 24 will have touched upon the top of plateau 12b,
and heat bonded into unity with the parts of the tubing 10 formed
to the illustrated moment. The secondary ribbon 24 (and tubing 10)
includes plural spaced apart grooves 26 each bounded by a
respective rib part 28 of the secondary ribbon 24. As is seen in
FIG. 2 at the next lap joint location 16 to the left (i.e., near
the left margin of FIG. 2), disposed within these grooves 26 of the
secondary ribbon 24 and separated from one another by the ribs 28
are individual conductors 30 (viewing FIGS. 2 and 5). Conductors 30
may be electrical conductors, or optical conductors, or a
combination thereof. It will be understood that the conductors 30
are also wrapped into the grooves 26 as the progressively forming
tubing 10 spins, which spinning is caused by the wrapping rolls
described earlier.
[0033] FIG. 2 also shows that very shortly after the placement of
the conductors 30 within grooves 26 of the secondary ribbon 24, a
bead portion 32 is extruded (i.e., molten plastic) and is disposed
on top of the secondary ribbon 24 and conductors 30. The moment of
touch down of the bead portion 32 atop of the secondary ribbon 24
is depicted in FIG. 5. As FIG. 5 shows, this bead portion 32 in
combination with the plateau portion 12b of primary ribbon 12', and
the fine-dimension secondary ribbon 24, defines the rib 14 seen on
the outside of tubing 10 in FIG. 1. FIG. 6 illustrates that the
plastic components of the tubing 10 heat bond with one another into
an integral unitary whole, including therein the conductors 22 and
30.
[0034] Considering now FIGS. 7 and 8 in conjunction with one
another, and viewing first FIG. 7, it is seen that the making of an
alternative embodiment of tubing 110 is depicted. Because this
alternative embodiment of tubing 110 includes many features that
are the same as, or which are analogous in structure or function
to, those of the first embodiment of FIGS. 1-6, these features are
referenced by the same numeral used above, and increased by
one-hundred (100). The tubing 110 has an exterior appearance
essentially the same as conventional tubing of this type, and the
same as the tubing 10 of FIGS. 1-6. That is, the tubing 110 has a
comparatively thin and flexible wall 112, and a helical bead 114
protruding somewhat above this wall and extending helically about
and along the length of the tubing. The tubing 110 also includes
embedded conductors extending helically in the bead 114 and along
the length of tubing 110 from end to end, as will be further
explained.
[0035] Viewing now FIG. 7, (which much like FIG. 2) illustrates
both structures as well as steps in the process of making an
inventive tubing 110, it is seen that the wall 112 is formed by
successive helical wraps of an elongate thin thermoplastic primary
ribbon 112'. Primary ribbon 112' also includes a thin wall portion
112a, and a plateau portion 112b defining plural spaced apart
grooves 118 each bounded by a respective rib part 120 of the
plateau portion 112b. Disposed within these grooves 118 and
separated from one another by the ribs 120 are individual
conductors 122. A thin, elongate, secondary ribbon 124 is placed on
top of the plateau 112b, and interbonds with this plateau 112b.
[0036] This secondary ribbon 124, in contrast to the ribbon 24 of
the first embodiment, is substantially flat at the time it is
extruded, does not define elongate grooves, but is conformal to the
shape of the plateau 112b upon which it is placed (including the
conductors 122) as is more fully explained below. More
particularly, the secondary ribbon 124 is conformal to the
stiffness or resistance to deformation of the plateau 112b.
Accordingly, considering that the plastic material forming the
tubing 110 is at this time yet molten to a degree, the conductors
122 form or define "hard" spots in the forming tubing structure.
And, in contrast, the molten plastic material adjacent to the
conductors 122 forms "softer" or compliant structure. As a result,
the secondary ribbon 124 which is molten and under tension as it
winds about the forming tubing structure, tends to pull inwardly
between the spaced apart conductors 122, and to remain piled up
over these conductors 122. Thus, although the secondary ribbon 124
is not extruded with grooves on its top (i.e., radially outward)
surface as was the case with the secondary ribbon in the first
embodiment, once the secondary ribbon 124 is pulled into place atop
of the plateau 112b, as is seen in FIG. 7, it forms a pair of
spaced apart elongate helical recesses (indicated with the arrowed
numerals 126) in its upper (i.e., radially outer) surface. These
recesses 126 have the effect of guiding the conductors to be placed
on the secondary ribbon 124, much as did the grooves 26 of the
first embodiment.
[0037] Disposed within the recesses 126 of the secondary ribbon 124
are a pair of individual conductors 130 (viewing FIGS. 7 and 8). It
will be understood that the conductors 130 are also wrapped into
the recesses 126 as the progressively forming tubing 110 spins,
which spinning is caused by the wrapping rolls described earlier.
FIG. 7 also shows that very shortly after the placement of the
conductors 130 within recesses 126 of the secondary ribbon 124, a
bead portion 132 is extruded (i.e., molten plastic) and is disposed
on top of the secondary ribbon 124 and conductors 130. As is by now
well understood, the plastic components of the tubing 110 heat
bond, and form a unitary integral structure, which is tubing
110.
[0038] Turning now to a consideration of FIG. 9 it is seen that the
making of yet another alternative embodiment of tubing 210 is
depicted. Because this alternative embodiment of tubing 210 also
includes features that are the same as, or which are analogous in
structure or function to, those of the first and second embodiments
of FIGS. 1-6, and of FIGS. 7 and 8, these features are referenced
by the same numeral used above, and increased by two-hundred (200).
The tubing 210 has an exterior appearance essentially the same as
conventional tubing of this type, and the same as the tubing 10 and
110 of the Figures discussed and described above. The making of the
tubing 210 of FIG. 9 is depicted as a sequence of "layers" much as
that presented in FIGS. 2 and 7, but with the manufacturing process
already well understood by the reader so that just the layering
together of extruded plastic ribbons and conductors is depicted in
FIG. 9. That is, the tubing 210 has a comparatively thin and
flexible wall 212, and a helical bead 214 protruding somewhat above
this wall and extending helically about and along the length of the
tubing. The tubing 210 also includes embedded conductors extending
helically in the bead 214 and along the length of tubing 210 from
end to end.
[0039] Continuing to viewing FIG. 9, both structures as well as
steps in the process of making an inventive tubing 210 are
illustrated. In FIG. 9 it is seen that the wall 212 is formed by
successive helical wraps of an elongate thin thermoplastic primary
ribbon 212' just as was the wall 12 of FIG. 2. It will be
understood by the reader that FIG. 9 illustrates a condensed
version of the successive manufacturing steps, which steps are
shown successively in FIGS. 2 and 7. A primary ribbon 212' also
includes a thin wall portion 212a, and a plateau portion 212b
defining plural spaced apart grooves 218 each bounded by a
respective rib part 220 of the plateau portion 212b. Disposed
within these grooves 218 and separated from one another by the ribs
220 are individual conductors 222. A thin, elongate, secondary
ribbon 224 is placed on top of the plateau 212b, and interbonds
with this plateau 212b.
[0040] This secondary ribbon 224, is similar to the ribbon of the
first embodiment of FIGS. 1-6, but defines only a single elongate
groove 226 bounded on each side by a respective rib part 228 of the
secondary ribbon 224. As is seen in FIG. 9, disposed within this
groove 226 of the secondary ribbon 224 is a twisted pair conductor
set 230. In other words, the twisted pair conductor set 230
consists of a pair of individual insulated conductors twisted about
one another and disposed in the groove 226. Such a twisted pair
conductor set has unique advantages in terms of limiting capacitive
and inductive couplings to adjacent conductors and to environmental
electro-magnetic interference sources. Thus, the twisted pair
conductor 230 has unique advantages for instrumentation and
telemetry uses of the tubing 210. As is described above (and which
by now is familiar to the reader) the twisted pair conductor set
230 is also wrapped into the groove 226 as the progressively
forming tubing 210 spins, which spinning is caused by the wrapping
rolls described earlier.
[0041] FIG. 9 also shows that very shortly after the placement of
the twisted pair conductor set 230 within recess 226 of the
secondary ribbon 224, a bead portion 232 is extruded (i.e., molten
plastic) and is disposed on top of the secondary ribbon 224 and
twisted pair conductor set 230. As is by now well understood, the
plastic components of the tubing 210 heat bond to one another as
they touch, and form a unitary whole which is integral.
[0042] It will be understood that during and after formation of the
tubings 10, 110, 210 as described above, the tubing is subjected to
cooling, which may include a conduit disposed within the winding
head and which sprays water directed radially outwardly against the
inner surface of the tubing as it forms (i.e., water spray "W"
described by reference to FIG. 1). Also, to the left (i.e., in the
direction of axial movement of the forming tubing) of the
manufacturing steps indicated in FIGS. 2, 7, and 9 (i.e., outside
of the view of these Figures) is conventionally disposed a cooling
trough containing water into which the tubing enters as it proceeds
leftwardly (recalling the motion arrow on FIG. 2). The cooling
water in this trough finishes cooling of the tubing product from
its molten condition to a finished flexible plastic integral
tubular product. Conventionally, the tubing is then cut into
pre-selected lengths for storage or shipment in a box.
[0043] The resulting tubing 10, 110, 210 includes a thin flexible
wall section (for example, formed by the portion 12a of ribbon 12'
apart from the plateau portion 12b) extending between adjacent
wraps of the bead 14, as is seen best in FIG. 1. This thin flexible
wall portion provides for exceptional flexibility for the tubing,
while the bead 14 provides support for the wall so that the tubing
is kink and collapse-resistant. Also, the conductors disposed
within the bead 14 are uniformly spaced apart as they extend
helically along the tubing within the plateau portion 12b captured
within the bead 14. This spacing apart of the conductors 16
provides a number of benefits. When a pair of the conductors are
employed for electrical resistance heating, the heating is more
dispersed than with conventional tubing. Similarly, the electrical
properties of the conductors when used to convey electrical signals
is favorable to this use. And, telemetry or instrumentation signals
(i.e., light, fiber optic, or electrical) may be conducted along
the conductors. Moreover, the spacing apart of these conductors
ensures both improved insulation of the conductors from one
another, an improved capacitance value between the conductors (and
improved uniformity of this capacitance value), and reduced mutual
inductive coupling among the conductors. Particularly with respect
to the embodiment of FIG. 9, the twisted pair conductor set
provides advantages for signal transmission which are well
understood in the fields of telephony and telemetry. Finally, the
inventive tubing product here disclosed provides unique advantages
because of the dual-level disposition of the conductors at the bead
of the tubing, and the resulting greater number of conductors which
this new tubing structure and product can provide.
[0044] While exemplary forms or embodiments of the invention has
been shown in the drawings and described herein, variations from
these exemplary forms will be apparent to those skilled in the art.
For example, a tubing providing only a twisted pair conductor set
disposed within a bead of the tubing is clearly within the ambit of
this invention. Similarly, a tubing having conductors disposed
within a bead structure of the tubing and at differing radial
levels relative to the center of the tubing is also part of this
invention. The invention therefore should not be construed as
limited to the specific forms shown and described, but instead as
is set forth in the following claims, which provide a definition of
the invention.
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